Optical coherence tomography (OCT) is currently actively introduced into clinical practice. Besides diagnostics, it can be efficiently employed for treatment monitoring allowing for timely correction of the treatment procedure. In monitoring of photodynamic therapy (PDT) traditionally employed fluorescence imaging (FI) can benefit from complementary use of OCT. Additional diagnostic efficiency can be derived from numerical processing of optical diagnostics data providing more information compared to visual evaluation. In this paper we report on application of OCT together with numerical processing for clinical diagnostic in gynecology and otolaryngology, for monitoring of PDT in otolaryngology and on OCT and FI applications in clinical and aesthetic dermatology. Image numerical processing and quantification provides increase in diagnostic accuracy. Keywords: optical coherence tomography, fluorescence imaging, photod
In this paper we report on our recent achievement in application of conventional and cross-polarization OCT (CP OCT) modalities for in vivo clinical diagnostics in different medical areas including gynecology, dermatology, and stomatology. In gynecology, CP OCT was employed for diagnosing fallopian tubes and cervix; in dermatology OCT for monitoring of treatment of psoriasis, scleroderma and atopic dermatitis; and in stomatology for diagnosis of oral diseases. For all considered application, we propose and develop different image processing methods which enhance the diagnostic value of the technique. In particular, we use histogram analysis, Fourier analysis and neural networks, thus calculating different tissue characteristics as revealed by OCT’s polarization evolution. These approaches enable improved OCT image quantification and increase its resultant diagnostic accuracy.
Gynecologic applications of optical coherence tomography (OCT) are usually performed in combination with routine
diagnostic procedures: laparoscopy and colposcopy. In combination with laparoscopy OCT is employed for inspection of
fallopian tubes in cases of unrecognized infertility while in colposcopy it is used to identify cervix pathologies including
cancer. In this paper we discuss methods for increasing diagnostic efficacy of OCT application in these procedures. For
OCT-laparoscopy we demonstrate independent criteria for pathology recognition which allow to increase accuracy of
diagnostics. For OCT-colposcopy we report on application of device for controlled compression allowing to sense the
elasticity of the inspected cervix area and distinguish between neoplasia and inflammatory processes.
KEYWORDS: Optical coherence tomography, Monte Carlo methods, Rectum, Skin, Scattering, In vivo imaging, Photons, Image compression, Multiple scattering, Optical properties
Contrasting of biotissue layers in OCT images after application of mechanical compression is discussed. The study is
performed on ex vivo samples of human rectum, and in vivo on skin of human volunteers. We show that mechanical
compression provides contrasting of biotissue layer boundaries due to different mechanical properties of layers. We
show that alteration of pressure from 0 up to 0.45 N/mm2 causes contrast increase from 1 to 10 dB in OCT imaging of
human rectum ex vivo. Results of ex vivo studies are in good agreement with Monte Carlo simulations. Application of
pressure of 0.45 N/mm2 causes increase in contrast of epidermis-dermis junction in OCT-images of human skin in vivo
for about 10 dB.
In the current paper we present preliminary data demonstrating therapeutic efficiency of local laser hyperthermia of
mouse tumors with gold nanoparticles. Measuring the tumor temperatures both superficial and inner by means of
standard NIR-thermograph and original acoustic thermometer correspondingly we show that the gold nanoparticles
increase thermal sensitivity of tumor tissue. Transmission electron microscopy and histopathology of the tumor tissue
indicated that the mechanism of apoptotic death of tumor cells is triggered following the laser treatment. 5 days after the
treatment tumor growth inhibition was 104 %.
The study was performed on 16 CBA-line female mice with transplanted cervical cancer. 0.2 ml of gold
nanoparticle solution with a concentration of 109 particles/ml were injected into the animals intravenously. The particles
were 200-250 nm in size; the plasmon-resonance related extinction maximum was at the wavelength of 850-950 nm.
Accumulation of the nanoparticles into tumor node was visualized by the method of optical coherence tomography
(OCT). When the accumulation of nanoparticles in the tumor was maximal, hyperthermia was accomplished using the
LSP-AZOR laser setup generating cw radiation at 810 nm. The duration of exposition was 20 min. The therapeutical
effect was assessed by the rate of tumor growth inhibition (TGI, %).
Determining the instant when nanoparticle concentration in tumor tissue reaches its maximum enables more
efficient laser impact. The use of nanoparticles decreases laser irradiation power and ensures local action.
KEYWORDS: Optical coherence tomography, Rectum, Monte Carlo methods, Image compression, Tissues, Optical properties, In vivo imaging, Skin, Inflammation, Diagnostics
The paper discusses application of mechanical compression for contrasting structural components of biotissues with
different mechanical properties in optical coherence tomography (OCT) images. Ex vivo study on human rectum samples
and in vivo study on human thin skin samples are performed. It is shown that for ex vivo sample the contrast between
epithelial and stroma layers increases with increase in applied pressure. For in vivo sample it is shown that at weak
constant applied pressure the contrast between epidermal and dermal layer increases exhibiting maximum after 2-3
minutes since pressure application. Monte Carlo simulations of OCT images of human rectum sample at different
compression levels is performed in order to confirm the origin of contrast. The results of simulations qualitatively agree
with experimental data.
KEYWORDS: Nanoparticles, Skin, Optical coherence tomography, Monte Carlo methods, Gold, Particles, In vivo imaging, Optical properties, Scattering, Titanium dioxide
Contrasting of skin forming elements in optical coherence tomography (OCT) images after application of silica/gold
nanoshells or titanium dioxide nanoparticles in solution is discussed. The study is performed both by Monte Carlo
simulations and in vivo on animals. The result show that application of both types of nanoparticles produces contrast
increase in the OCT images of skin. The increase in OCT signal level originates from the higher backscattering on
nanoparticles compared to that on skin forming elements. The increase of contrast in the OCT images originates from the
difference in nanoparticles concentration within different skin constituents. These experimental results are confirmed
qualitatively by Monte Carlo simulations based on multilayer skin model.
Dynamics of nanoparticles penetrating and accumulating in healthy (skin) and pathologically altered (tumor)
tissue was investigated in vivo by the method of optical coherence tomography (OCT). Gold nanoshells having the size
of 130/15 nm and titanium dioxide nanoparticles 40-100 nm in size were studied. Nanoparticles accumulation in
biotissue was accompanied by the change of optical effects in OCT images. Continuous OCT monitoring of the process
of nanoparticles penetration into skin showed that optical effects appeared 30 minutes after application of nanoparticles
on the surface; maximal effect of nanoparticles accumulation in the skin was recorded in the observation period of 1.5-5
hours.
Nanoparticles accumulation in neoplastic tissue at passive delivery was studied in vivo. Accumulation maximum
was 4-6 hours after intravenous introduction.
The transmission electron microscopy technique confirmed accumulation of nanoparticles in biotissues.
We propose to realize an endoscopic all-fiber clinical device for polarized reflectance spectroscopy based on
polarization-maintaining (PM) fiber. Results of testing the above device in model media and the first data of clinical
investigations are presented.
Investigations in vivo were carried out on the uterine cervix with benign and malignant alterations. 7 female patients
were examined. POR technique confirm a possibility of differentiating neoplastic changes by the depolarization ratio.
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